One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,6)(4,5)(7,8)(17,18)(19,21)(20,22)(23,24)(25,26,28,30)(27,33,34,40)(29,37,36,32)(31,38,39,35)(2,5)(6,8)(9,10,12,14)(11,15,16,13)(17,19,20,23)(18,21,22,24)(26,30)(31,39)(32,37)(33,40)(3,7)(6,8)(9,11,12,16)(10,13,14,15)(25,27)(26,31)(28,34)(29,38)(30,39)(32,40)(33,37)(35,36)(1,3,4,7)(2,6,5,8)(18,22)(21,24)(27,34)(31,39)(33,40)(35,38)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.